Such valve devices serve to control pressure of hydraulic controllers, for example, in control units for automatic gearboxes or for regulating the pressure in a control chamber of a variable oil pump of an oil circuit for lubricating an internal combustion engine of a vehicle. Via the pressure in the control chamber, a ring of a feed chamber, on which the rotor of a rotary vane pump or a gear pump rolls, is displaced or turned, thereby changing the volumetric capacity.
The pressure regulating valves used for these purposes comprise, for example, an electromagnetic valve which is connected via a lateral connection with a storage tank and whose lower connection is connected via an orifice to the outlet of a hydraulic fluid source. A pressure connection of a consumer to be regulated is arranged between the valve and the fluid source, wherein the pressure is adapted to be adjusted depending on the position of the electromagnet and thus the valve closing element.
A similar pressure control valve is described in EP 0451 272 A1. This valve comprises a lateral pressure connection and a lateral outlet to the storage tank as well as a lower regulating pressure connection. Depending on the position of the valve element, a free cross section of different size from the pressure connection to the outlet or to the regulating pressure connection exists, via which the pressure at the regulating pressure connection can be adjusted.
DE 11 2008 000 978 T5 describes a system for controlling the pressure in two control chambers of an oil pump using an electromagnetic valve and a spring-loaded slider member, wherein, depending on the feed pressure and the position of the electromagnetic valve, the differential pressure between the two control chambers is changed. This system additionally comprises a pressure relief valve via which the oil can be returned from the discharge side of the pump to the suction side in the case of excessive feed pressure.
These known valves and systems are disadvantageous in that the functions of overpressure switch-off and pressure regulation are performed in different components, and the free cross section allowing a flow-through, and thus the flow at the valve and the velocity and possible pressure adjustment amplitude of the pressure regulation, are relatively small. In pressure regulating valves, the required armature opening force in particular depends on the magnitude of the overpressure.